Organic light-emitting device

Abstract

Provided is an organic light-emitting device including: an anode; a cathode facing the anode; two or more light-emitting layers provided between the anode and the cathode and each having a maximum light emission peak of ≤500 nm (≤500 nm emission layer); and a light-emitting layer provided between the two or more ≤500 nm emission layers, and having a maximum light emission peak at >500 nm (>500 nm emission layer), where a distance from the anode to the ≤500 nm emission layer most adjacent to the anode is 100 nm to 200 nm, the distance from the anode to the ≤500 nm emission most adjacent to the cathode is three to four times the distance from the anode to the ≤500 nm emission layer most adjacent to the anode, and an N-type charge generation layer including an alkali metal and a P-type charge generation layer including a material with an electron affinity of ≥4.8 eV are provided between each of the ≤500 nm emission layers and the emission >500 nm emission layer.

The invention claimed is: 
     
       1. An organic light emitting device comprising:
 an anode; 
 a cathode provided to face the anode; 
 two or more light emitting layers provided between the anode and the cathode and each having a maximum light emission peak at a wavelength of 500 nm or less; and 
 a light emitting layer having a maximum light emission peak at a wavelength of more than 500 nm provided between the two or more light emitting layers each having a maximum light emission peak at a wavelength of 500 nm or less, 
 wherein a distance from the anode to the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the anode, is 100 nm to 200 nm, 
 a distance from the anode to the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the cathode, is 3 times to 4 times the distance from the anode to the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the anode, 
 an N-type charge generation layer and a P-type charge generation layer are provided between each of the light emitting layers each having a maximum light emission peak at a wavelength of 500 nm or less and the light emitting layer having a maximum light emission peak at a wavelength of more than 500 nm, and 
 the N-type charge generation layer comprises an alkali metal, and the P-type charge generation layer comprises a material having an electron affinity of 4.8 eV or more, 
 wherein the distance from the anode to the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the anode means the distance from an interface between the anode and a layer which is adjacent to a side of the anode, which faces the cathode to an interface between the light emitting layer having a maximum light emission peak at 500 nm or less, which is the most adjacent to the anode, and the layer which is adjacent to the side of the anode, which faces the cathode, and 
 wherein the distance from the anode to the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the cathode means the distance from the interface between the anode and the layer which is adjacent to the side of the anode, which faces the cathode to an interface between the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the cathode, and a layer which is adjacent to a side of the light emitting layer having a maximum light emission peak at a wavelength of 500 nm or less, which is the most adjacent to the cathode, which faces the anode. 
 
     
     
       2. The organic light emitting device of  claim 1 , wherein an intensity of the maximum light emission peak at a wavelength of 500 nm or less is 1.5 times or more an intensity of the maximum light emission peak at a wavelength of more than 500 nm in the entire light emitting spectrum of the organic light emitting device. 
     
     
       3. The organic light emitting device of  claim 1 , wherein an electron transport layer is provided at a cathode side of each the light emitting layers, and a hole transport layer is provided at an anode side of each of the light emitting layers. 
     
     
       4. The organic light emitting device of  claim 3 , wherein a hole transport layer which is the most adjacent to the anode among the hole transport layers is in contact with the anode, an electron transport layer which is the most adjacent to the cathode among the electron transport layers is in contact with the cathode, and the hole transport layer which is the most adjacent to the anode or the electron transport layer which is the most adjacent to the cathode comprises two or more materials. 
     
     
       5. The organic light emitting device of  claim 3 , wherein:
 a hole transport layer which is the most adjacent to the anode among the hole transport layers is in contact with the anode; 
 an electron transport layer which is the most adjacent to the cathode among the electron transport layers is in contact with the cathode; and 
 the hole transport layer which is the most adjacent to the anode and the electron transport layer which is the most adjacent to the cathode comprise two or more materials. 
 
     
     
       6. The organic light emitting device of  claim 1 , wherein the light emitting layers each having a maximum light emission peak at a wavelength of 500 nm or less are each composed of two or more layers, or each comprises two or more host materials. 
     
     
       7. The organic light emitting device of  claim 1 , wherein the light emitting layer having a maximum light emission peak at a wavelength of more than 500 nm is composed of two or more layers, and one or more layers of the two or more layers comprises two or more hosts. 
     
     
       8. The organic light emitting device of  claim 1 , wherein the material having an electron affinity of 4.8 eV or more is 
       
         
           
           
               
               
           
         
       
     
     
       9. The organic light emitting device of  claim 1 , wherein the P-type charge generation layer comprises a material having an electron affinity of 4.8 eV in combination with a carbazole derivative or an amine derivative. 
     
     
       10. The organic light emitting device of  claim 9 , wherein the carbazole derivative is: 
       
         
           
           
               
               
           
         
       
     
     
       11. The organic light emitting device of  claim 10 , wherein the P-type charge generation layer comprises: 
       
         
           
           
               
               
           
         
       
     
     
       12. The organic light emitting device of  claim 1 , wherein an intensity of the maximum light emission peak at a wavelength of 500 nm or less is 2 times to 3.5 times an intensity of the maximum light emission peak at a wavelength of more than 500 nm in the entire light emitting spectrum of the organic light emitting device.